Piston



2 Sheets-Sheet 1 INVENTOR.

ATTORN Elbert Jfliall M1 72" E. J. HALL April 19, 1927.

PISTON Filed April 18, 1923 1,625,120 E. J. HALL PISTON April 19, 1927.v

Filed April 1a,- 192: 2 Sheets-Sheet 2 l1 i i' MI MN l "16m; 1} w 15 Hin n INVENTOR. llberi Iflall '41 ATTOR EYS.

Patented Apr. 19, 1927.

um] ED STATES PATENT OFFICE.

ELBEB'J. J. HALL, OF BERKELEY, CALIFORNIA.

PISTON.

Application filed April 18, 1923. Serial No. 632,914.

This invention relates to pistons for internal combustion engines, andhas for lts object to reduce piston slap and to dampen T o overcome thisI providethe piston with a movable segmental portion in the side of theskirt opposite that receiving the power stroke thrust and arrange asprlng back of this movable segmental portion to yieldingly force thesame outwardly. Not only does this movable segmental portion absorb the,

slap tending to occur in a direction at right angles to the axis of thewrist pin, but, if the width of the movable portion be extended towithin a short distance of the pin bosses, any tendency of the pistonto' slap in a direction parallel with the axis of the wrist pin can beprevented. The action of this segmental portion can also be improved byutilizing oil to act as a check or cushion against inward movement ofthe said movable member.

In the accompanying drawings- Fig. 1 shows a central, vertical,sectional view of the piston embodying one form of my invention;

Fig. 2 shows a plan sectional view of the same.

Fig. 3 shows a vertical, central, sectional view of a modified form ofthe piston.

Fig. 4 shows a plan sectional view of the form illustrated in Fig. 3.

The piston may be of any improved design and of any desired material. Inthat side of the skirt opposite the side receiving the thrust on thepower stroke is .a separate segmental portion 10 fitted slidabl into arecess in the skirt'of the piston. surface of this segmental portion isground on an arc of the same diameter as the cylinder bore. Back of thesegmental portion is a light coil spring 11 abutting against the wall ofthe piston skirt and tending to force the movable segmental portionoutwardly.

In the form shown in Figs. 1 and 2 this I he outer segmental portion isprovided with a chamber 12 in which the spring is seated and a duct 13communicates with this chamber, said duct leading to the outside of thepis-, ton at a point immediately below the piston rings. Oil on thecylinder walls is thus admitted to the chamber 12 and acts as a check orcushion against inward movement of the segmental portion 10.

In Figs. 3 and 4, I show the piston cut away at oneside and a separatesegmental portion 14 slidably fitted into guides 15 surrounding said cutaway portion. In this form of the invention I showa bowed leaf spring 16abutting against the opposite wall of the piston and extending, over thepiston pin and pressing against the inside of the segmental portion 14.

In the operation of the piston the spring forces the movable se mentalportion outwardly against the cylinder wall when the thrust is acting inthe opposite direction on 1 the piston. As the iston rod passes over thecenter and the irection of the thrust is reversed the segmental portionwill move inwardly against the spring. The effect of the heat is toweaken or lessen the resistance of the spring so that the spring may becomparatively stifi' when the piston is relatively cool and-of lessresistance when the piston is hot. Thus the movable segmental portionwill be held closely in contact with the cylinder wall when the pistonis cool, while, at the same time, when the piston expands under highertemperatures, the spring will readily yield to allow the movablesegmental portion to move inwardly."

In the form shown in Fi 1, where the oil chamber 12 is provide thischamber will become filled with oil when the segmental portion 10 movesoutwardly. The oil therein will act as a check or cushion against inwardmovement of the segmental portion. The tendency of the piston to slapthe cylinder walls will be overcome with the arrangement shown herein,and, likewise, vi-

brations occurring in the operation of the piston will be considerabldampened. The width of the mova le segmental portionmay vary, but bywidening it to withcover about one-third the circumference of the pistonthe slap in all directions will be prevented. I v I I prefer to make thespring 16'of thermostatic metal, that is, having an inner layer 16 ofless coefficient of expansion than the outer layer 16". The effect ofthis is to draw the spring in, When heated, and thus lessen the outwardpressure exerted by the spring upon the movable segment when the pistonbecomes hot. i v 7 'It is to be noted that the movable segmentterminates above the bottom'of the skirt of the piston so that theentire cirrumference of the lower part of the piston skirt is leftintact, thus preserving the strength of the piston,

Various changes in the. construction and arrangement of the severalparts herein shown and described may be employed Without departingfromthe spirit of my invention as disclosed in the appended claim. 7

Having thus described my invention, what 1 claim and desire to secure byLetters Patcut is A piston for internal combustion engines having nearits upper portion a groove for retaining a scraper ring, a movablesegmental portion forming part of the piston v skirt, a chamber tocontain oil arranged between the segmental portion and the wall ofthepiston, and a duct leading from said chamber to the outside of thepiston adja cent the scraper ring groove, whereby oil scraped by thering will be admitted to the chamber for the purpose of forming a checkagainst inward movement of the segmental portion.

ELBERT J. HALL.

